Asthma Subgroups: Severe Allergic Asthma
A common asthma subgroup is allergic asthma. It usually presents as mild or moderate asthma, but sometimes it presents as severe allergic asthma. Here’s what to know.
What is allergic asthma?
It affects about 50% of asthmatics, and is the most common asthma subgroup diagnosed before the age of 12.1 It's when you have asthma plus allergies. Common allergies are to dust mites, mold spores, animal dander, pollen, and cockroaches. You can also have allergies to certain food.
Allergic asthma usually diagnosed before the age of 6, and definitely by the age of 12. It tends to be mild or moderate, and is completely reversible with either time or treatment. The most common asthma triggers are the allergens listed above. Another common trigger is respiratory viruses. So, it often comes with a second diagnosis of Virus-Induced Asthma. It's also often coupled with exercise induced or rhinitis induced Asthma.
What is the treatment of allergic asthma?
Acute symptoms respond well to beta-adrenergic medicine (such as albuterol) It’s usually easy to control with a daily regimen of inhaled corticosteroids. When controlled, asthma symptoms should be rare. They should be mild when they do occur, and reversible with treatment.2
What is severe allergic asthma?
It's when you have asthma plus two or more allergies. These allergies may tend to be more severe. When exposed to them, their airways are quick to respond. Asthma attacks occur with increased frequency and severity.2 It's rare to have severe allergic asthma. So, no one knows how many there are.1
Why does allergic asthma progress to severe asthma?
Researchers don't know the answer to this. It may be due to a massive exposure to an allergen. It may also be due to a respiratory virus, like a bad cold or pneumonia. It may have something to do with certain asthma genes. It may be a combination of the above-listed theories. It may be something else altogether, like Th2 high asthma.2
What does Th2 high mean?
It’s an umbrella term under which allergic asthma falls. Th2 high means that the person has a very high amount of Th2 cytokine in their airways (IL4, IL5, and IL13). This may be coupled with an elevated number of mast cells that release these cytokines. Th2 cytokines are tiny proteins released during allergy and asthma attacks. They cause airway inflammation and asthma. Lots of these cytokines may cause asthma to become persistent and severe. They may also cause airway remodeling, which can make asthma severe. I find this theory very interesting, so look for me to expound upon it in a future post.2
What is the treatment for severe allergic asthma?
It presents with eosinophilic inflammation during allergy or asthma attacks. These eosinophils and Th2 Cytokines respond very well to inhaled corticosteroids. Severe asthma attacks respond well to systemic corticosteroids. It may also respond well to medicines like Singular and Xolair. There are currently other medicines in the pipeline that should also prove useful.
Can you control severe allergic asthma?
Controlling asthma also means controlling allergies. This usually entails two or more asthma medicines. Even when controlled, asthma episodes may still occur when exposed to your triggers. If controlled, symptoms should be mild and reversible with treatment.
What to make of this?
Again, most people with allergic asthma have mild asthma. Some may have moderate. Only a small percentage have severe asthma. It usually has a very good prognosis. This is because it is well understood by researchers and doctors. And because there are many treatment options for it. So, this means that a good asthma treatment regimen should result in good asthma control.
What has your experience with Singulair been like?